Commit c1f06161 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: intel8x0: Don't update period unless prepared 



The interrupt handler of intel8x0 calls snd_intel8x0_update() whenever
the hardware sets the corresponding status bit for each stream.  This
works fine for most cases as long as the hardware behaves properly.
But when the hardware gives a wrong bit set, this leads to a zero-
division Oops, and reportedly, this seems what happened on a VM.

For fixing the crash, this patch adds a internal flag indicating that
the stream is ready to be updated, and check it (as well as the flag
being in suspended) to ignore such spurious update.

Cc: <stable@vger.kernel.org>
Reported-and-tested-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Link: https://lore.kernel.org/r/s5h5yzi7uh0.wl-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 1d5cfca2

sound/pci/intel8x0.c

+7 −0
Original line number Diff line number Diff line
@@ -331,6 +331,7 @@ struct ichdev { 
	unsigned int ali_slot;			/* ALI DMA slot */

	struct ac97_pcm *pcm;

	int pcm_open_flag;

	unsigned int prepared:1;

	unsigned int suspended: 1;

};
@@ -691,6 +692,9 @@ static inline void snd_intel8x0_update(struct intel8x0 *chip, struct ichdev *ich 
	int status, civ, i, step;

	int ack = 0;



	if (!ichdev->prepared || ichdev->suspended)

		return;



	spin_lock_irqsave(&chip->reg_lock, flags);

	status = igetbyte(chip, port + ichdev->roff_sr);

	civ = igetbyte(chip, port + ICH_REG_OFF_CIV);
@@ -881,6 +885,7 @@ static int snd_intel8x0_hw_params(struct snd_pcm_substream *substream, 
	if (ichdev->pcm_open_flag) {

		snd_ac97_pcm_close(ichdev->pcm);

		ichdev->pcm_open_flag = 0;

		ichdev->prepared = 0;

	}

	err = snd_ac97_pcm_open(ichdev->pcm, params_rate(hw_params),

				params_channels(hw_params),
@@ -902,6 +907,7 @@ static int snd_intel8x0_hw_free(struct snd_pcm_substream *substream) 
	if (ichdev->pcm_open_flag) {

		snd_ac97_pcm_close(ichdev->pcm);

		ichdev->pcm_open_flag = 0;

		ichdev->prepared = 0;

	}

	return 0;

}
@@ -976,6 +982,7 @@ static int snd_intel8x0_pcm_prepare(struct snd_pcm_substream *substream) 
			ichdev->pos_shift = (runtime->sample_bits > 16) ? 2 : 1;

	}

	snd_intel8x0_setup_periods(chip, ichdev);

	ichdev->prepared = 1;

	return 0;

}